The present invention, in some embodiments thereof, relates to imaging and, more particularly, but not exclusively, to a method and system for correcting image distortion.
Digital cameras are used for still photography and videography and the captured digital images may be transferred to an image display device such as a monitor. Due to imperfections and natural limitations of cameras' optical system, the digital images displayed on a monitor may show geometrical distortions. Geometrical distortions are a class of optical aberrations that occur when the object is not situated on the optical axis of the camera's lens system. Geometrical distortions depend on the angle that a ray incident on the lens makes with the optical axis.
Rapid advancement in high resolution sensors, based on either charged couple device (CCD) or complementary metal oxide semiconductor (CMOS) technology, has made digital still camera and video recorders popular and affordable. The sensor technology follows the long standing semiconductor trend of increasing density and reducing cost at a very rapid pace. However, the cost of digital still camera and the video recorders do not follow the same steep curve. The reason is the optical system used in the image acquisition systems has become the bottleneck both in performance and in cost. A typical variable focus and variable zoom optical system has more than a dozen lenses. While the number of pixel lines and pixel resolution rapidly increase, the precision of optical components fail to keep the pace since the optical technology does not evolve as fast as the semiconductor technology.
Precision optical parts with tight tolerances are expensive to make, and it is difficult to maintain focus, spherical aberration, centering, chromatic aberrations, astigmatism, distortion, and color convergence within a tight tolerance even after very careful assembly process.
In digital imaging, an image can be processed for correcting optical distortion by a data processor. In the field of digital imaging, techniques relating to the correction of optical distortion have conventionally been proposed.
U.S. Pat. No. 5,276,519 discloses a video image capture apparatus for digitally compensating imperfections introduced by an optical system. The apparatus includes an image sensor for sensing light at a plurality of pixel positions received via the optical system, picture storage means for temporarily storing pixels derived from the image sensor, and address generation means for applying differing write and read addresses to the picture storage to effect mapping of input pixels from the image sensor to provide output pixels compensating for the effects of imperfections of the optical system.
U.S. Pat. No. 5,465,121 discloses a system for compensating distortions resulting from a projection of an image source onto a surface that is not perpendicular to an image source projection system. A data processing system image source data file is identified and a test pattern is displayed utilizing a data processing system visual output device. A user is able to enter a distortion compensation factor and the displayed test pattern is modified utilizing the distortion compensation factor. Once a final distortion compensation factor has been selected by the user in response to the appearance of the modified test pattern, the data processing system image source data file is modified utilizing the selected distortion compensation factor.